CFD Performance Comparison Between GPU and CPU

For the GPU Technology Conference 2013 (GTC13) I performed a series of simulations in Caedium comparing the OpenFOAM® linear solver GPU option using ofgpu with the standard CPU shared memory option using MPI. See selected slides and the presentation deck below.




Clearly there is still more work to do to make the GPU accelerated linear solvers competitive with the highly optimized MPI compatibility in OpenFOAM. The good news is that the NVIDIA CUDA software continues to improve with each new release and the GPU hardware performance is increasing faster than Moore's Law.

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OpenFOAM on GPU vs CPU


I am just wondering that why a GPU code with slower than CPU. On its face, it seems that GPU has more no. of cores and sufficient memory (6 GB) to run a simulation of 4 M cells. Could you just tell the reason why it is slower?